Communication system



5 Sheets-Sheet l m not W. H. T. HOLDEN COMMUNICATION SYSTEM Filed May 5, 1942 Nov. 2, 1943.

lNVE/VTOR W H 7. HOLDEN W W m 1943- w. H. T. HOLDEN 2,333,179

COMMUNICATION SYSTEM Filed May 5, 1942 5 Sheets-Sheet 2 ATTORNEY Nov. 2, 1943. w. H. T. HOLDEN COMMUNICATION SYSTEM Filed May 5, 1942 5 SheetS-Sheet 5 w F p w h P P p w w W i A I I t m g m m m m M H h M M h h /NVENTOR B W H T HOLDEN A T TORNEV FIG. 4

Nov. 2, 1943. w HOLDEN 2,333,179

COMMUNICATION SYSTEM Filed May 5, 1942 5 Shets-Sheer, 4

W H T HOLDEN MW MT A NORA/E Y Nov. 2, 1943. w. H. T. HOLDEN COMMUNICATION SYSTEM 5 Sheets-Sheet 5 Filed May 5, 1942 /N W: N TOR W H 7.' HOLDEN ATTORNEY Patented Nov. 2, 1943 2,333,179 COMMUNICATION SYSTEM William H. T. Holden,

to Bell Telephone New York, N Y., a

WVoodside, N; Y., assignor Laboratories, Incorporated, corporation of New York Appiication May 5, 1942, Serial No. 441,786

V '2 Claims.

This invention relates to communication systems and particularly to telephone systems in which connections are established automatically. An object of the invention is to effect economies by minimizing the amount of controlling equipment used in the establishment of the connections. V More specifically anobject of the invention is to omit certain essential routing equipment.

from each of the severalv switch-controlling markers in an automatic telephone oflice and to provide a single one of "these routing equipments for the common use of all markers.

Another object isto simplify these systems still further by. dispensing with the conventional switching devices for connecting the several markers to'the common routing equipmentiand by utilizing discriminating signals to obviate interference in theuse of this common .equipment.

A still further object is to enable all of the switch-controlling markers in concurrent usexto have access to the common-routing equipment without waiting and without interference with each other.

These and-otherobjects of the invention are realizediby means of a system in which a group of route tubes of-the discharge type are provided in common to a number of switch-controlling markers for determining the routes over which the desired connections are to be established. This common group of route tubes is accessible to the markers over a permanent wire multiple interconnecting the-group of tubes with each of the several markers having access thereto. Since two or more of the markers may be-in use con-.- currently, it is desirable that eachma-rker have access to the route tubes without being required to wait for other markers. This free access with out interference is accomplished by utilizing a system of signaling between the markers andv the route tubes in which signals of different phases are provided, each marker being characterized by aparticular phase, for transmitting the information from the marker to the route tubes. to determine the selection of the desired one and for transmitting the decoded information from the selected tube back to the particular marker that seized the tube. Inasmuch as theseveral mark ers concurrently in use are in communication with the route tubes in successive phases, no interference exists-between the markers, and each marker is free to seize, inits own phase; any one of the tubes and to receivethe necessary informaticn from that tubewithout interference either with or from other markers. In fact, two or more markers concurrently in use may avail themselvesof the same route tube without interference'. I

These and other features of theinvention-will be discussed more fully in the following detailed specification. a

In the drawings accompanying the detailed specification:

Figs. 1 to 5, when arranged in the order indicated in Fig. 6, illustrate a portion of an automatic telephone system in which the present invention is embodied.

Fig. 1 shows a calling su'bscribers line; a line switch, district and ofiice selector switches, two central office senders and connecting 'devices for 1 said senders Figs; 2 and .3 illustrate-two switch-controlling markers. Fig.t2 also shows an impulse generator for supplying impulses to the" markers; .and

Figs. 4 and 5 illustrate a, plurality of route tubes common to the switch-controlling markers together with "aconnecting multiple for joining these tubes to all of the markers.

Automatictelephone systems of the crossbar type now in use comprise a. number of central office register senders and anumber of common markers for controlling the selective" operation of the crossbar switches to establishthe desired connections. The designations'tra'nsmitted over the subscribers lines by dial impulses are first received and registered in the'senders. The sender thus taken in use associates itself with an idle one of the markers and 'trans'mitsthereto' that part of the entire designation which represents the ofiice code or the routeover which the call is to be extended toward the called line. The marker receives this information and uses it to select and operate a number of route relays, the relay thus chosen representing the particular route overwhich the call is to'be extended. The operated route relay in the marker serves to determine the association of the marker With the desired trunk group for testing purposes and also causes signals to be transmitted back into' the sender to register therein the various types of route information which the sender requires in order to proceed with the further extension of the call; In areas involving a multiplicity of offices the markers in any particular oflice may be called upon to route the calls over a large number of outgoing trunkgroups, thus requiring a correspondingly large number of route relays and associated connections in each'marker pro vided :in the office. a

As previously explained the system disclosed herein contemplates the saving of the numerous route relays now provided in each of the central office markers by substituting a common group of route tubes of the discharge type, all of which are readily accessible to any marker that requires route information. Moreover, these common route tubes are connected to the several markers by means of a permanent set of multiple conductors rather thanthe relay or switch type of connector that is usually employed for making connections with common equipment. Notwithtanding this permanent connection between the markers and the common route tubes, no interference occurs between the markers although a number of them may be working concurrently on calls. This freedom from interference is achieved by utilizing a system of signaling between the markers and the route tubes in which impulses of different phases are employed, each phase being: individual to and characterizing a particular one of the markers. 'Thus two or more jmarkers working concurrently on separate calls make use of the same tubes in the common group] in their own'separate phases without interference.

Inasmuch as the present invention is concerned, particularly withthe routing equipment associated with the markers, it is not considered necessary to disclose the details of the other parts of the system. However, an understanding of a system of the crossbar type to which the invention may be applied may be had from. the patent to Carpenter.'2,235,8()3 of March 18, 1941.

Referring to'the drawings for a general understandingof the present system, a subscribers line I00, appearing in a frame of line switches ll. V

has access over district trunks I02 to a frame of district switches m3 and also through a sender connector :I 04.to an idle one of anumber of senders I05, I06.. The district switches I03 haveaccess through the switches of an oilice frame l0! to trunks I08, 109 outgoing over a large number of routes to terminating switching equipment in the same or in distant ofiices. The central 0ffice, in which these switches and senders are located, is also provided with a plurality of switchcontrolling' markers 200, 300. Any one of the senders may: seize any idle one of these markers and connect itself thereto through the marker connectors H0, Ill.

Each ofthe markers is provided with registers for receiving and registering the office code designation. This code designation is transmitted to the marker from the sender together with other information concerning the class of the calling line and the identity of the district frame to which the calling'line has been extended. For example, the marker 200 is provided with registers 201, 202 and 203 for registering the three digits of the oiiice code. Each of these registers comprises a series of ten space discharge tubes, only ,three tubes .per register being illustrated in the drawing. The register 2M may serve to register the class information concerning the calling line, and, as above noted, other registers may be provided in the marker for receiving further information concerning the call from the sender.

Each of the markers is also equipped with a plurality of registers for receiving and storing the decoded information from the route tubes. In the marker 200, threeof these registers, 205, 205 and 201, are illustrated. Each-of these registers comprises a plurality of discharge tubes, there being as many tubes as are necessary to store the information received from the route tubes. The registers 205, 206, 201 serve to control the connection of the marker to the switch frames for testing the desired group of trunks to make the necessary comparisons between the class of the calling line and the class of the office to which connection is attempted, and to transfer back to the sender all information required by thesender for controlling the further extensionof the call in the distant offices.

The marker 300, like marker 200, is also provided with registers 30L 302, 303, 304, which receive theoffice code and other information from the sender, and with registers 305, 306, 30'! which receive thedecoded information from the common group of route tubes.

All 'of the markers 200, 300, etc., in the office are provided with a common group of route tubes including the tubes 400, MM, 500 and 50!, there being one of these tubes for each route over which 'calls'may be extended. The route'tubes are selected and operated by the markers over a common wire multiple 403 which is permanently connected to the; code registers of all markers and to the control electrodes of all route tubes. The multiple 403 consists of three groups of conductors 404, 405 and 406, each group having ten conductors therein. The ten conductors in the group 404 are connected through condensers to the main cathodes of the ten respective tubes of the first office code register 20! inthe marker 200 and in multiple to the tubes of register 30I of marker 300 and to the tubes of the corresponding register of all other markers Lin: the office. The ten conductors of the second group'y405 are connected through condenser to' the cathodes of the ten respective tube'stof the second ofiicecode' register 202 of marker 200, in multiple to the tubes of the register 302 of marker 300, and similarly to the registers of all other markers. In like manner the ten conductors of the third group 406 are connected to the tubes of the third code registers 203, 303, etc., in the respective markers. Each one of the thirty multiple conductors 403 is connected through an individual one of a group of resistors 502 to the negative pole of the biasing battery 503," the positive'pole of battery 503 being connected to the negative pole of the anode battery 504. When an office code registration is set up on the registers 20L 202 and 203, or on the corresponding registers in any other marker, the discharge of the operated register tubes in the phase assigned to that particular marker causes current to flow over one of the conductors in each of the three groups 404, 405 and 406 through the resistors 502 to batteries 503 and 504. This current flow through the resistors 502 sets up potentials On the multiple conductors 403, and these potentials are applied to'the control electrodes of the route tubes in a manner now to be described.

The control electrodes of the route tubes 40!), 4!, 402, etc., are connected in varying combinations, each electrode to a particular combination of three of the multiple conductors 403. Since there are thirty of these conductors, ten for the ten decimal values of each of the three places of the ofiice code, the route tube for any particular ofiice code is determined byconnecting the control electrode of that tube tothe three corresponding decimal conductors in the group of thirty. For example, if tube 402 represents office code' 091 the control electrode 407 of this tube is connected as shown through resistors 408,

s lh connecteu through 409 andx4l0 to theLN'o/O conductor..4lil.rinithe first-group 404; to'theNo. '9 conductor4l2 in the second group 405, and to-the No. 1 conductor M3 in the third group 405 Similarly, if route-tube 40l: represents the oifice code 190, its control electrode'4l4-is connected through the resistors-415, M6 and 4|"! totheNoxl conductor 4| 8; to the No.- 9'conductor "4| 2, and to the No. 0 conductor 420i Likewisetube 501, which represents oflice code 910 has its control electrode resistors 505, 506 and 507 to the No. 9 conductor 4H), to the No. 1 "condu'ctor 421, and to the No: 0 conductor 420. And

in like manner all of the remaining route tubes in the common group have their control electrodes connected indifferent combinations to the multiple conductors 403.

The route tubes 400, 40l, 402, etc., whichare preferably of the vacuum typ'e; including. a cathode, a control electrode or grid, and a plurality of anodes. The biasing battery 503 is applied across the cathode and control grid of all tubes, and normally these tubes do not conduct. In order to cause one of the tubes to conductit is necessary to apply to its grid a positivepotential equal in value'to the full potential that exists on the multiple conductors403 when current is flowing therein from the register tubes in one of the markers; If a lesser positiv'epoconduct. i Route ,tube-40l also has itscontrol electrode'connected through resistor 4!;6 toconductor'4l2 on which potential exists under-this assumption, but no potential is present on the other two conductors M8 and 420- to which electrode M4 is connected. Therefore, circuitsmay be traced for the flow of current from conductor 4l2 through resistance :MB and in parallel through resistances 415 and 4i 1,-conduct0rs 4H! and 420., resistors 508 and 500 to batteries 503 and504. 'Accordingly the full potential onconductor 4 I 2- is not applied to the electrode 444, andthe tube 40I does not' conduct. In likemam tubes will'have their control electrodes connected to one or two of the conductors 4H, M2, M3 withthe'result that full potential is notapplie'd tojany oneof these tubes. Hence, only the tube 402 will operate in response to the application of potential to these three conductors. This method of selection by the use of varying potentials; in which incrementsvarying from zero potential up to the full operating value are applied to a plurality of tubes, is described more fully in the patent to L. A. Meacham, No. 2,317,471 of April 27, 1943.

'I'herouting information determined by the operated route'tubes is transferred back to the markers over a second conductonmultiple 422 which is permanently connected between the anodesof the routertubes and the registersin marker and the the markers towhi'ch tlieroutingiinformation'is transferred. Thev wire multiple 422 isidivided into as many groups 423, 424, 425', etc; as there are .items of routing information required by the associated sender. Only the three groups 423, 424, and 425 have been illustrated, and these are connected to the three associated registers 205, 206 and 201 in themarker 200 to the registers 305,306 and 301 inthe marker 300 and to corresponding registers in all other markers. The number of conductors in each of these groups will depend upon the number of tubes needed in the associated register'to register the route information. Three are shown, and as many more as necessarywill be provide'dy but usually the information canbe expressed in some code requiring less-than tenconductors and associa-tedregister tubes. Each ofthe multiple conductors 422 is connected: through an individual resistor to ground'in order that current flowing. in'these resistors will develop potentials on the conductors which serve to ionize the tubes'in the marker registers. I

The. anodes of the route tubes are connected to the conductors of the groups 423, 424 and 425 in combinations that represent the items of information to be transferred back to the markers. For example, the anodes 426 and? of tube 402 are connected to conductors 428'and odes of tubes. 208 and 2000f thewmarker' register 205. Anodes 430Jand 43| areconnected to multiple conductors 432 and 433 of the second group 424, and these conductors are connected tothe starting electrodes of tubes 210 and 2H of register 206. Anodes 434, 435 and436 of the'tube' 402 are connected to=conductors 431, 438 and439 of the third group 425, and these in turn are conneoted to the starting cathodes of tubes 2|2, H3, and 254 of the :register 201. I Similarly other anodes in the tube 402 may be connected to the conductors of other groups for the operation of corresponding registers in the marker. Since the conductors 422 aremultipledto all markers,

in the marker 200. i The detailed operating circuits for these register tubes .will be described morefullyhereinatteri Since' the different route tubes 400, 40!;402, 500

) a system-of s-igna'lingin' which a characteristic The'signal impulses of the several phases are produced by an impulse generator 2!!) supplied with a source of alternating current 2H3. During each cycle of the source 216 signal impulses of the successive phases are produced in the impulse leads 2l1, and these impulses are delivered in'succession to the respective markers. Each marker in use causes the transmission of impulses of its phase to the multiple conductors 403 for the purpose of selecting the route tube representing theofiice code registered in the marker, and the operated route tube causes the transmission of impulses of the same phase over conductors 422 to selectand operate the proper tubes inthe route information registers of that marker.

To explain the operation of the system more fully it will be assumed that the subscriber of line I00 wishes to call a subscriber whose line has the office designation 09l. In response to the initiation of the call the line I00 is extended through the line switch frame |0I to an idle trunk 02 and thence through a sender selector I04 to an idle register sender I06. After the designation has been received in the sender I06, the

connector Ill operates to connect the sender to an idle marker 200. Thereupon the operated registers in the sender I06 cause the application of positive. andnegative potentials to the conductors2l8 in combination such that the starting gaps of the No. .0 tube 2 I 9 of register 20l, the No. 9 tube 220 of register 202, and. the No. 1 tube 221 of register 203 are ionized. Also the starting gaps of the proper tubes in each of the remaining registers 204, etc., are ionized 'over the conductors 218. As soon as the starting gaps of these register tubes are ionized, current flowsv from the positive pole ofbattery 222 through the contacts of relayr223, transformer winding 224,

conductor 225 thence through the main anodes of the ionized tubes to the'main cathodes of these tubes and thence through the individual resistors to ground. In this manner the selected tubes are operated and their main gaps are ion ized by current flowing from the anode battery 222. However, the potential applied to the corresponding conductors of the multiple 403 is insufficient to cause the operation of the route tubes. Thus the ofiice code designation is transferred and registered in the marker together with any other information such as the class of the calling line, district frame number, etc., that may be required by the marker.

As soon, following the ionization of register tubes 2|9, 220 and 22l, as the generator 2l5i enters the phase allotted to the marker 200, an impulse is sent out from the generator over impulse lead 226, through the transformer winding 228 to ground. The current impulse flowing in the winding 228 induces an impulse in winding 224, and this impulse is transmitted through the conducting tubes 2I9, 220 and 221 through the respective condensers 229, 230 and 23l to the multiple conductors 4| L4" and M3. These impulses flow through the resistors SH, 512 and 513 to batteries 503 and 504, and in so doing 'set up equal potentials on the conductors 41 I, M2 and M3. Since these potentials are all equal, no current flows through resistors 408, 409 and M0,

. and the full value of the potential isapplied to the grid 401. The potential thus'applied to grid 401 being positive, the bias of battery 503 is overcome, and the tube 402 passes current between its cathode and its several anodes. The circuit for the flow of anode current in the tube 402 may be tracedfrom the negativepole of battery 504, conductor 514, cathode 440,-anodes'426, 421, 430, 431, 434, 435 and 436 thence over conductors 428, 429, 432, 433, 431, 438 and 439 through resistors 515, 516, 511, 518, 519, 520 and 521 to the ground ed or positive pole of battery 504. Each time the impulse generator 215 passes through the phase of marker 200, the tube 402 conducts, and current impulses flow through the resistors 515, 5I6, 511, etc. The flow of these current impulses through the resistors lowers the potential of the corresponding conductors of the multiple 422 to a given value, and these negative potential impulses are applied to the starting cathodes of the registers 205, 206 and 201 and to the corresponding registers in other markers. More specifically, the negative potential impulses appearing on conductors 428, 429, 432, 433, 431, 430 and 439 are applied respectively to the starting cathodes of tubes 208, 209, 2l0, 2, 212, H3 and 214. At the same instant that. these negative potential impulses are being applied to the starting cathodes of the tubes in marker 200, positive impulses of the same phase are also being applied over conductor 221 to the starting anodes of the register tubes in this marker. The sum of the positive and negative impulses on the cathodes and anodes being sufficient to cause ionization, tubes 203, 209, 2l0, 2| I, 212, 2 l3 and 214 ionize, whereas all other tubes of these registers remain inert. Although the negative impulses on conductors 428, 429, 432, etc., are applied to the starting cathodes of the tubes in the other markers these impulses do not correspond in phase with the positive impulses that are being applied to the starting anodes of these tubes. Consequently only the code information registers 205, 206, and 201 in the marker 200 are affected by the operated route tube 402.

At the time the marker 200-is causing the repeated operation of route tube 402, once per cycle of the source 216, and is receiving the code information impulses of like phase from the route tube, another marker, such as the marker 300, may also be in the process of operating one of the route tubes for a similar purpose. If, for example, the marker 300 has been seized by a sender I05, the registered information in the sender is transferred to the code registers 30!, 302, 303, 304 of marker 300, and at each cycle of the source 2l6 an impulse of the phase which characterizes the marker 300 is delivered over impulse conductor 232 to the operated tubes of the registers 30!, 302, 303 and to the starting anodes of the route information registers 305, 306 and 301. The impulses passing through the, operated tubes of registers 30f, 302, 303 cause the application of potentials to the multiple conductors 403 in a combination which results in the operation of the desired one of the route tubes, and the operated route tube returns the routing information over the multiple conductors 422 to cause the operation of the proper ones of the tubes of registers 305, 306 and 301. No interference takes place between the markers 200 and 300 although they are both making use of the common multiple conductors 433 and 422 and may even be operating the same route tube. They do not interfere for the reason that each marker has its own individual phase, and during the brief interval of that particular phase the marker has exclusive use of the common multiple conductors and the common route tubes.

Returning to the call which it is assumed that the line I00 is making, as soon as the marker 200 receives the routing information from the tube 402, it proceeds. to connect ritselt ktorthe district and: ofljlce frames 51.03 andl-lllfl and to transfer certain routing information back into the sender I06. The marker controls the 'setting ofswitches lll3and -l01 to extend the trunk-I02 to the desired-outgoing trunk, such-as :the trunk I08. Thereafter th'esender'rlflfi controls the completion' of the connectlong the connector HI releases :the marker 200, and the latter irestores to its normal condition. The operated-tubes in the marker; which. are preferably 1 of the gas-filled type, maybe released any well-known inanner. \Forexample; the operateditubes in the registersflzl[ 202,103are.:restored .by operating the relayi223 to opent-he anodeicircuitse of: these tubes; i lfhemegisteritubes, disclosed herein may; bev of anyisuitable type; Preferably they have separate starting 1.18am. andsrmain, discharge: aps. For a tter, understandin of a .t. be;Q -thi.swt.yp ref: ere ce s made to herpatentto "1- Hold n Not2273958501Fe ruary 2 yes-mention d her mbe ore, the route r t re s; are u.reiemmy-v of the vacuum type in order that they may be fast enough 1; follow 3; the 1 rapid 1 impulses delivered from the generator H5 and to conserve the holding time of the markers which make common use of these tubes.

What is claimed is:

1. The combination in a signaling and switchcontrolling system, in alent switch-controlling markers are provided for determining the routes over which connections are established in accordance with desired designations, of a group of route devices common to the use of all of said markers, each of said route devices characterizing a particular route over which connections may be set up under the control of said markers, means for seizing any one of said markers and for registering a desired designation therein, time-controlled means for seizing and operating the corresponding one of the route devices in said common group, and means efiective in response to the operated route device for transmitting back to the marker that seized it routing information required by the marker for establishing the connection represented by said desired designation.

2. The combination in a signaling and switchcontrolling system, in which a plurality of switchcontrolling markers are provided for controlling the establishment of connections over the routes represented by desired designations, of a group of route devices common to the use of all of said markers, each of said route devices characterizing a particular route over which connections may be set up under the control of said markers, means for seizing any one of said makers and for registering a desired designation therein, means for generating impulses of each of a plurality of diflerent phases, said phases being assigned individually and respectively to said markers, means controlled in accordance with the designation registered in any one of said markers for selectively operating in phase with the impulses of the phase assigned to said marker the particular route device corresponding to the registered designation, and means effective in response to the operated route device for transmitting to said marker signals of the particular phase assigned thereto and representing the routing information required by the marker for establishing the desired connection.

3. The combination in a signaling and switch controlling system, in which a plurality of switchcontrolling markers are provided for controlling which a plurality of equiv the establishmentof connections overthe routes represented by, desired designations,;.of a: group ofroute discharge tubeslcommon tozallof said markers, each of said tubesrrepresentinga par; ticular route 'over which connections are exten'dedelundertm control of, any :oneci said markers, means for taking any one ofsaid markers=into use;and-pfor registering a desired designation; therein, means for; supplying each marl:-v er: .withn a; succession of impulses of a particular phase,:: the.-:phasexi assigned toreach marker difiering 'from those; oi" ,the cthenmarkers, wmeans controlled by any marker taken into ,use'for-selectI VGlY QDEZatiIIg aparticulan-one of said route ub s nphas w th th m u su plied; o s id marke andm ae efi lc ive 1. qns fi t e operated route tube for transmitting?- to said marker signals ofhthe phase assigned to said markerand representing ,the route, information required by the marker for establishingthe desiredconnectionr Q f I Q4; ,The, combination ,in a switch con TQl1iI s s mtli h h a? lu al t equ a ent marke e' js eer v dd f te i e t e o t s ove which connections are established in accordance with the desired'designations, of a group of route tubes common to all said markers, each of said tubes characterizing a particular route over controlled by any one of said route tubes when operated in any one of said phases for establishing in the particular marker to which the phase is assigned the routing information required by the marker for establishing the connection represented by the designation registered therein.

5. The combination in a switch-controlling system, in which a plurality of equivalent markers are provided for'determining the routes over which connections are established in accordance with desired designations, of a group of route tubes common to all said markers, each of said tubes characterizing a particular route over which connections may be extended under the control of any one, of said markers, means for seizing a plurality of said markers for concurrent use and for registering designations in the markers thus seized, means for supplying each marker with impulses of a particular phase, the phase assigned to each marker differing from that assigned to other markers, at set of circuit conductors connecting the route tubes of said group in permanent multiple relation to all of said markers, means effective in accordance with the designation registered in each one of said markers for applying to said multiple conductors impulses of the phase assigned to such marker to operate selectively the particularroute tube representing the route of the designation registered in said marker, and means effective in response to the operation of any route tube in any one of said phases for transmitting impulses of such phase over said multipleconductors to establish in the particular marker to which such phase is assigned" the routing inseized' it routing information irequired' by .the formation required by the marker-for establishmarker; for; establishing the connection reping-the connection represented by the designaresentedaby said desired "designation.-

tion registered therein. t '1. The combination in azsignaling and switch- 6. The combination in a signaling and switch- 5 controlling system,'in whicha plurality of equivcontrolling system, in which a plurality of equivalent switchecontrolli'ng markers arepro'vided for alent' switch-controlling markers are provided determining the. routes over which connections for determining the routes over which connecare established in accordance-.with desired destions are established in accordance with desired ignations, of a plurality of dischargetubes com designations,of a group of route devices'common 1n mon to the use, of all of said markers, each tube to-the' use of all of said markers, each of said serving to characterize a particular route 'over route devices characterizing a particular route which connections 'may'b' p under'the over which connections--may be set up under trol of said markers, meansior'seizingany one the control of said markers, multiple conducoflsaid markers and. for registeringa desireddes tors permar'ie'ntly joining all markers with each ignation therein, means controlled in accordance of said route devices}- means for seizing any one with the registered J'designation' for seizing and of said markers and for registering a desired desoperating the corresponding one of said route ignation therein, means dependent on the registubes, and means effective in response to the tered designation for applying to said multiple operated route tube 'for transmittingbacl; to the conductors signal potentials for seizing and oper- 51, marker that seized it routing information reating the particular route device which correquired by the marker for establishing the consponds to the registered designation; and means neetion represented by id esir d desi nation efiective'in response to the operated route dle- Y vice for transmitting back to the marker that W L M HIT. HOLDE 

